Thanks Ray. It does live in fresh water, but will go in salt on occasion. Im concerned that now that it has t-stats, water pressure will be to high, and Ive never installed relief valves. So Im wondering what is the easiest way to plumb them.

Thanks for the info.... I have been looking at oil thermostats, for the cost and time to install I wondered if just by-passing the oil cooler might do the trick?

Sorry about the thread hijack Kreed, it was just that your initial question was foremost in my mind right now......I am trying to answer similar questions to yours...

No problem!

[QUOTE=FogduckerIII;3361839]Thanks for the info.... I have been looking at oil thermostats, for the cost and time to install I wondered if just by-passing the oil cooler might do the trick?

If you can size the oil cooler accurately, you should be able to eliminate the oil cooler. I would say that if you can hold your typical WOT run to under 240 degrees (short period), you are good. It sounds like your current oil cooler may to be big. Big is good only if you have a oil thermostat.

[QUOTE=BenPerfected;3361976]Stock Mercruiser oil cooler......I think I will try with it by-passed, I will not remove it, just the lines, if the temps are not right I can always hook it back up and go the oil thermostat route.......friggin boats......

I'm slowly working up to trying to get my engines to run at a stable 180F water temp, a little bit at a time.

Even though as some say here oil temp is most important, seems to me that aiming for 210 - 220 oil temp but running at 160 or less water temp is a contrast in efficiency. One is trying to fight the other.

The closer you can get them both to where they really want to be, that being closer to each other but still running in an efficient temp zone for cooling and lubrication, the happier the engine will be. And, its easier to control each temp if closer to the other.

I can't help but cringe a bit seeing my engines running at over 5000rpm with only 140F water temp. Cylinder wall temps surely aren't as warm as they need to be when surrounded by a waterjacket to promote good long term piston ring wear. Not to mention valve guides, or hot valves closing on super cooled valve seats etc.

Hence my personal goal to see a stable 170 to 180F with 140F thermostats and a few 1/8" bypass holes in them.

Maybe I'm talking out my azz. But its what makes logical sense to me based on experience outside the marine world. Only time will tell if I'm really an idiot or not

I have 540s with alu heads,no t stat water temp 120 max oil temp 190 after a hard run,oil temp is key for wear cool water temp helps with detionation when running high comp,cool air will make more power but that is hard in a boat seeing we boat in warm weather,4 seasons no problems want to add motor is closed cooled my 2 cents

Rookie,
You are not likely an idiot, but you might be missing the point on oil temp's. I am from the school that says in a HP marine application that parts like the valve train are going to wear out well before the rings. Many believe the water temp isn't a big deal at anywhere between 100 -160. To remove the water from condensation and maybe small internal leaks out of the oil, you need a way to get the oil temp to 212+ on a regular basis. IMO, how you are you going to manage the oil temp is more important that the water temp. Even Mercury used a oil temp thermostat on the 500HP.

Actually no benefit quite the opposite in fact . On my truck I feel safe at oil temps at 180 but getting to 220 I start to ease up on the throttle If I just can high temps just kills the additives first. But keeping the engine otherwise hot as possible (water) makes more power if you can control it.
Smokey Yunick tried all his life to control high temps and run on the brink of detonation.. his Hot Vapor Engines was something to think about...
http://www.legendarycollectorcars.co...clusive-video/

Well, I'll throw in my .02. Living in the land of NASCAR, I talk to engine guys all the time, and some of the best know names are here. They run (IMO) pretty much like we do - at or near full load for hours - on high compression, carbed engines.

None of the guys I've asked run coolant temps under190 or so, and several things I've read or beeen told indicate they make best power at 210. They of course want oil temps at about the same. These are small blocks turning out 850hp for hours at a time.

So, I agree with Rookie: if you are not using forced induction and low temps for detonation control, you should be in the 160+ range. I run 170 at sustained WOT, oil temps peak ~220 (slightly high IMO). No issues, and I've noticed a bonus of decreased fuel burn.

I've heard Merc used the 143 stats to decrease salt damage in salt/brackish water, so perhaps that is where the 140 came from.